Python determines leap year

#-*- coding:utf-8 -*-
try:
  year = int(raw_input('请输入年份(如2008): '))
except:
  print '请输入正确的年份'
  exit()
is_leap = False
if year % 100 == 0 and year % 400 == 0:
  is_leap = True
elif year % 100 != 0 and year % 4 == 0:
  is_leap = True
if is_leap:
  print '%d年是闰年！' % year
else:
  print '%d年不是闰年！' % year